In the middle of the lower register, Van Eyck painted two trompe-l'oeil sandstone sculptures. They represent the two saints who figured so prominently in both the commisioning and content of the work. the young mpan portrayed on this panel is the Apostle John - writer of one of the four Gospels and tradionally identified as the author of the 'Revelation of John' or the Apocalypse. His presence in the painting is, therefore, entirely natural. John the Evangelist is shown holding a chalice containing poisonous adders. The image refers to an early legend, in which John is said to have drunk from a poisoned cup yet survived.